There is provided herein a dryer polymer substance adapted to pervaporate a fluid (such as water, water vapor or both), the polymer substance includes: a porous support member having a plurality of pores, wherein at least a portion of the pores are filled with a cross-linked co-polymer comprising (i) a cationic monomer and an anionic monomer, (ii) a zwitterionic monomer, or a combination thereof. The substance may include a membrane or a tube. There is further provided herein a process for the preparation of a dryer polymer substance adapted to pervaporate a fluid (such as water, water vapor or both), the process includes impregnating into at least a portion of the pores of a porous support member a solution which comprises: (i) a cationic monomer and an anionic monomer, (ii) a zwitterionic monomer, or a combination of (i) and (ii), graft co-polymerizing the anionic monomer and the cationic monomer and/or the zwitterionic monomer within at least a portion of the pores to form a co-polymer, and cross-linking the co-polymer, such that the pores of the support member are at least partially grafted with a cross-linked co-polymer bound to the support member.